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noise to signal ratio

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longhaireddwb said:
Your right. I didn't read it all. Just read what I thought I needed too. :redface:

I did this just a few minutes ago. Put the 1Khz signal from the program into the generator. Re adjusted everything and did this with the volume as low as I could make it on the radio. I had to go with -90dbm to get the sinad program to read enough to adjust. And still the spectrum is all over the place. This is picture #1.

I then turned the volume all the way down so no signal was making it to the program and I still had noise all over the spectrum. This is picture #2.

I dont understand why this is. I must have a noisy computer is all I can think of.
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You might be right about the computer being the problem.
Try feeding the tone from the sound card directly into the input of the sound card..... SINAD display should be great with only one vertical pip on the display.
In other words, do not take the recovered audio from the radio and feed it into the input of the SINAD meter, but take the cable that you used to send the 1kc tone to the generator and put it into the SINAD meter input.
I hate to say this (not) but there might be some trouble shooting/testing recommendations in the operations manual for the SINAD software program.
We are not going to fail at this, only the test equipment can fail us.
Let's keep trying till we determine what is the problem.
 
I looked into changing the tone to 1Khz and I even dug up a pot to put in but I don't have an O-scope that is worth a damn. I have two of them and both of them don't work as they should. I hate buying from E-bay!

From the manual:
Mod Jacks on front - Input jacks for external Modulation and output jacks for 400hz tone.

I did try and take the 1khz tone right out of the computer and right bck into the computer and it showed a nice fine line at the 1khz on the spectrum.
Hum? Looked good there.
 
Robb said:
The 'EXT MOD' is an outgoing signal; not for an incoming signal. You might want to read the owners manual.

http://www.freeinfostuff.com/E200D/e-200d_manual.pdf

E-200D 1KHz Modulation

If you turned down the radio volume; then the incoming signal is distorted because a) you have the output too high from the sig/gen b) the radios audio output signal is noisy c) Q9 is having thermal issues (most likely).

http://www.freeinfostuff.com/E200D/e-200d_bulletin.pdf
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Sorry Robb I am gonna have to disagree with you on this one.
INT is for the internal 400 cps tone to modulate the generator carrier, 400 Hz OUT is to send the internal modulation audio tone to the EXT MOD terminals to be used for auxilliary purposes and the EXT is for to modulate the generator carrier from an external audio source via the EXT MOD terminals
 
I think now my problem is with the signal generator. I guess I should see if I can find another one. Another item I got taken on from e-bay.

Anyone have any ideas of where to find another generator that will work at a good price besides ebay?:crying:
 
longhaireddwb said:
I think now my problem is with the signal generator. I guess I should see if I can find another one. Another item I got taken on from e-bay.

Anyone have any ideas of where to find another generator that will work at a good price besides ebay?:crying:
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That isn't going to be easy nor cheap. Hunted high and low for a long time until finding a quality generator for a low price. Got it local; you might find something in CO Springs. But wouldn't recommend buying one if you can't test it first. Set my sights on a Hp.

The Hp's go for $300 to $450, but there are other brands. A Marconi is one; Klondike Mike has one. Imagine G0HZU and others can give you some other ideas for other brands/models that are of a decent quality.
 
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I'n going to ask around town and a few HAMS I know. Maybe someone will have one for sale.

I do like the digital frequency readout on some of them. Hopefully that will show them better on the mark.
 
Trying to work out a deal on a hp8656a for 500 bucks. Hope i get it. Then i bet ill be able to get a good reading with the sinad. Ill keep you informed on how it comes out. Sure looks like a nice sig gen. :-):-):-)
 
Robb said:
Here are some screen captures of this program.

The radio being tested was a SuperStar JA that was discussed on another thread.

I used a 1uV 1khz 30% modulated signal from an Hp 8656B RF Sig Gen in AM mode for these results.
Click to expand...
Rob I’ve read a lot of your post and i bought a HP875B signal generator today and of course now I need a Sinad meter I found the sinad software and was curious about it and then seen where You seemed to like it I was wondering if it would work with. My laptop and if so what all will I need?hist the audio cord and isolator ? And how hard is it to set up and use ? Thanks
 
Corey stover said:
Rob I’ve read a lot of your post and i bought a HP875B signal generator today and of course now I need a Sinad meter I found the sinad software and was curious about it and then seen where You seemed to like it I was wondering if it would work with. My laptop and if so what all will I need?hist the audio cord and isolator ? And how hard is it to set up and use ? Thanks
Click to expand...
You mean that there are no YouTube videos on how to set it up?
It isn't rocket science we are talking about here, the writer of the software describes how to use it and the radio's service manual gives the parameters for the sig/gen settings. Other than that, it isn't so straightforward how to adjust the receive, there are some things to understand and some tricks to employ. Might check out YouTube for that info, since they can lay it out faster and to the point better than I can write up here.
 

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